EE 551/451, Fall, 2006 Communication Systems Zhu Han Department of Electrical and Computer Engineering Class 13 Oct. 3 rd, 2006.

Slides:



Advertisements
Similar presentations
Signal Encoding Techniques
Advertisements

Analogue to Digital Conversion (PCM and DM)
Physical Layer – Part 2 Data Encoding Techniques
CHAPTER 4 DIGITAL MODULATION Part 1.
ECE 4371, Fall 2009 Zhu Han Department of Electrical and Computer Engineering Class 8 Sep. 17 th, 2007.
4.2 Digital Transmission Pulse Modulation (Part 2.1)
DIGITAL COMMUNICATIONS.  The modern world is dependent on digital communications.  Radio, television and telephone systems were essentially analog in.
ECE 4371, Fall, 2014 Introduction to Telecommunication Engineering/Telecommunication Laboratory Zhu Han Department of Electrical and Computer Engineering.
4.2 Digital Transmission Pulse Modulation (Part 2.1)
Networks: Data Encoding1 Data Encoding Techniques.
EE2F1 Speech & Audio Technology Sept. 26, 2002 SLIDE 1 THE UNIVERSITY OF BIRMINGHAM ELECTRONIC, ELECTRICAL & COMPUTER ENGINEERING Digital Systems & Vision.
Physical Layer – Part 2 Data Encoding Techniques
Communication Systems
Data Encoding Techniques
Pulse Modulation CHAPTER 4 Part 3
Fundamental of Wireless Communications ELCT 332Fall C H A P T E R 6 SAMPLING AND ANALOG-TO-DIGITAL CONVERSION.
 Transmitting two or more signals simultaneously can be accomplished by setting up one transmitter- receiver pair for each channel, but this is an expensive.
Ch 6 Sampling and Analog-to-Digital Conversion
Chapter 4 Digital Transmission
331: STUDY DATA COMMUNICATIONS AND NETWORKS.  1. Discuss computer networks (5 hrs)  2. Discuss data communications (15 hrs)
Digital Communication Techniques
1/21 Chapter 5 – Signal Encoding and Modulation Techniques.
Formatting and Baseband Modulation
PULSE CODE MODULATION & SOURCE CODING Sampling Theory
Fundamentals of Digital Communication
Chapter Seven: Digital Communication
Digital multiplexers In TDM a group of analog signals are sampled sequentially in time at a common sampling rate and then multiplexed for transmission.
ECE 4371, Fall, 2014 Introduction to Telecommunication Engineering/Telecommunication Laboratory Zhu Han Department of Electrical and Computer Engineering.
Introduction to Communication Systems
LECTURE Copyright  1998, Texas Instruments Incorporated All Rights Reserved Encoding of Waveforms Encoding of Waveforms to Compress Information.
AUDIO COMPRESSION msccomputerscience.com. The process of digitizing audio signals is called PCM PCM involves sampling audio signal at minimum rate which.
Pulse Code Modulation (PCM)
10/6/2015 3:12 AM1 Data Encoding ─ Analog Data, Digital Signals (5.3) CSE 3213 Fall 2011.
نیمسال دوّم افشین همّت یار دانشکده مهندسی کامپیوتر ارتباطات داده (883-40) مدولاسیون پالس.
Signal Encoding Techniques. Lecture Learning Outcomes Be able to understand, appreciate and differentiate the different signal encoding criteria available.
Speech Coding Submitted To: Dr. Mohab Mangoud Submitted By: Nidal Ismail.
CE Digital Signal Processing Fall 1992 Waveform Coding Hossein Sameti Department of Computer Engineering Sharif University of Technology.
Chapter 5. Pulse Modulation
1 PCM & DPCM & DM. 2 Pulse-Code Modulation (PCM) : In PCM each sample of the signal is quantized to one of the amplitude levels, where B is the number.
Pulse Code Modulation (PCM)
Basic Encoding Techniques
Engineering and Physics University of Central Oklahoma Dr. Mohamed Bingabr Chapter 1 Introduction ENGR 4323/5323 Digital and Analog Communication.
CS Spring 2009 CS 414 – Multimedia Systems Design Lecture 3 – Digital Audio Representation Klara Nahrstedt Spring 2009.
Chapter 4 Digital Transmission. 4.#2 4-1 DIGITAL-TO-DIGITAL CONVERSION line coding, block coding, and scrambling. Line coding is always needed; block.
CHAPTER 3 DELTA MODULATION
ECE 4371, 2009 Class 9 Zhu Han Department of Electrical and Computer Engineering Class 9 Sep. 22 nd, 2009.
4.2 Digital Transmission Pulse Modulation Pulse Code Modulation
Delta modulation DM DM is a simple modulation scheme used to transmit one bit per sampling frequency In DM the analog information signal is oversampled.
Differentially Encoding
Chapter 4 Digital Transmission. 4.2 Summary Line Coding Line Coding Schemes Block Coding Scrambling Signal Element versus data element Multilevel : 2b1Q.
4.2 Digital Transmission Pulse Modulation Pulse Code Modulation
Data Communication, NUML-Islamabad
Fundamentals of Multimedia Chapter 6 Basics of Digital Audio Ze-Nian Li and Mark S. Drew 건국대학교 인터넷미디어공학부 임 창 훈.
1 st semester 1436 / Modulation Continuous wave (CW) modulation AM Angle modulation FM PM Pulse Modulation Analog Pulse Modulation PAMPPMPDM Digital.
1 Speech Compression (after first coding) By Allam Mousa Department of Telecommunication Engineering An Najah University SP_3_Compression.
Lifecycle from Sound to Digital to Sound. Characteristics of Sound Amplitude Wavelength (w) Frequency ( ) Timbre Hearing: [20Hz – 20KHz] Speech: [200Hz.
Figure 3–1 PAM signal with natural sampling.
4.2 Digital Transmission Pulse Modulation (Part 2.1)
Chapter 3 Pulse Modulation
Analog to digital conversion
UNIT – III I: Digital Transmission.
UNIT II.
Chapter 3 Pulse Modulation
Subject Name: Digital Communication Subject Code:10EC61
Physical Layer (Part 2) Data Encoding Techniques
Physical Layer – Part 2 Data Encoding Techniques
4.2 Digital Transmission Pulse Modulation (Part 2.1)
Chapter 10. Digital Signals
PCM & DPCM & DM.
Physical Layer – Part 2 Data Encoding Techniques
Presentation transcript:

EE 551/451, Fall, 2006 Communication Systems Zhu Han Department of Electrical and Computer Engineering Class 13 Oct. 3 rd, 2006

EE 541/451 Fall 2006 Pulse Code Modulation (PCM) Pulse code modulation (PCM) is produced by analog-to-digital conversion process. Quantized PAM As in the case of other pulse modulation techniques, the rate at which samples are taken and encoded must conform to the Nyquist sampling rate. The sampling rate must be greater than, twice the highest frequency in the analog signal, f s > 2f A (max) Telegraph time-division multiplex (TDM) was conveyed as early as 1853, by the American inventor M.B. Farmer. The electrical engineer W.M. Miner, in PCM was invented by the British engineer Alec Reeves in 1937 in France.Alec Reeves1937 It was not until about the middle of 1943 that the Bell Labs people became aware of the use of PCM binary coding as already proposed by Alec Reeves.Bell Labs

EE 541/451 Fall 2006 Figure The basic elements of a PCM system. Pulse Code Modulation

EE 541/451 Fall 2006 Encoding

EE 541/451 Fall 2006 Advantages of PCM 1. Robustness to noise and interference 2. Efficient regeneration 3. Efficient SNR and bandwidth trade-off 4. Uniform format 5. Ease add and drop 6. Secure DS0: a basic digital signaling rate of 64 kbit/s. To carry a typical phone call, the audio sound is digitized at an 8 kHz sample rate using 8-bit pulse-code modulation. 4K baseband, 8*6+1.8 dBdigitalsignalingkbit/skHzpulse-code modulation Virtues, Limitations and Modifications of PCM

EE 541/451 Fall 2006 Encode information in terms of signal transition; a transition is used to designate Symbol 0 Regeneration (reamplification, retiming, reshaping ) 3dB performance loss, easier decoder Differential Encoding

EE 541/451 Fall 2006 Consider a finite-duration impulse response (FIR) discrete-time filter which consists of three blocks : 1. Set of p ( p: prediction order) unit-delay elements (z -1 ) 2. Set of multipliers with coefficients w 1,w 2,…w p 3. Set of adders (  ) Linear Prediction Coding (LPC)

EE 541/451 Fall 2006 Block diagram illustrating the linear adaptive prediction process. Reduce the sampling rate

EE 541/451 Fall 2006 Differential Pulse-Code Modulation (DPCM) Usually PCM has the sampling rate higher than the Nyquist rate. The encode signal contains redundant information. DPCM can efficiently remove this redundancy. 32 Kbps for PCM Quality

EE 541/451 Fall 2006 Processing Gain

EE 541/451 Fall 2006 Need for coding speech at low bit rates, we have two aims in mind: 1. Remove redundancies from the speech signal as far as possible. 2. Assign the available bits in a perceptually efficient manner. Adaptive quantization with backward estimation (AQB). Adaptive Differential Pulse-Code Modulation (ADPCM)

EE 541/451 Fall 2006 ADPCM Adaptive prediction with backward estimation (APB) kbps with the same quality of PCM

EE 541/451 Fall 2006 Coded Excited Linear Prediction (CELP) Currently the most widely used speech coding algorithm Code books Vector Quantization <8kbps Compared to CD 44.1 k sampling 16 bits quantization kbps 100 times difference

EE 541/451 Fall 2006 Time-Division Multiplexing Figure Block diagram of TDM system.

EE 541/451 Fall 2006 DS1/T1/E1 Digital signal 1 (DS1, also known as T1) is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside of North America and Japan. Technically, DS1 is the transmission protocol used over a physical T1 line; however, the terms "DS1" and "T1" are often used interchangeably.T-carrierBell Labs telecommunicationsNorth AmericaJapanE1 A DS1 circuit is made up of twenty-four DS0circuit DS1: (8 bits/channel * 24 channels/frame + 1 framing bit) * 8000 frames/s = Mbit/s A E1 is made up of 32 DS0 The line data rate is Mbit/s which is split into 32 time slots, each being allocated 8 bits in turn. Thus each time slot sends and receives an 8-bit sample 8000 times per second (8 x 8000 x 32 = 2,048,000) Mbit/sMbit/s History page 274

EE 541/451 Fall 2006 Synchronization Super Frame

EE 541/451 Fall 2006 Synchronization Extended Super Frame

EE 541/451 Fall 2006 T Carrier System Twisted Wire to Cable System

EE 541/451 Fall 2006 Fiber Communication

EE 541/451 Fall 2006 Delta Modulation (DM)

EE 541/451 Fall 2006 DM System: Transmitter and Receiver.

EE 541/451 Fall 2006 The modulator consists of a comparator, a quantizer, and an accumulator. The output of the accumulator is Slope overload distortion and granular noise

EE 541/451 Fall 2006 Slope Overload Distortion and Granular Noise ( differentiator )

EE 541/451 Fall 2006 The modulation which has an integrator can relieve the draw back of delta modulation (differentiator) Beneficial effects of using integrator: 1. Pre-emphasize the low-frequency content 2. Increase correlation between adjacent samples (reduce the variance of the error signal at the quantizer input ) 3. Simplify receiver design Because the transmitter has an integrator, the receiver consists simply of a low-pass filter. (The differentiator in the conventional DM receiver is cancelled by the integrator ) Delta-Sigma modulation (sigma-delta modulation)

EE 541/451 Fall 2006 delta-sigma modulation system.

EE 541/451 Fall 2006 Adaptive Delta Modulation Adaptive adjust the step size according to frequency, figure 6.21 Out SNR –Page –For single integration case, (BT/B)^3 –For double integration case, (BT/B)^5 Comparison with PCM, figure 6.22 –Low quality has the advantages. –Used in walky-talky

EE 541/451 Fall 2006 Questions?